SSL/TLS Strong Encryption: Compatibility

This page covers backwards compatibility between mod_ssl and other
SSL solutions. mod_ssl is not the only SSL solution for Apache; four
additional products are (or were) also available: Ben Laurie's freely
available Apache-SSL (from
where mod_ssl were originally derived in 1998), Red Hat's commercial
Secure Web Server (which was based on mod_ssl), Covalent's commercial
Raven SSL Module (also based on
mod_ssl) and finally C2Net's (now Red Hat's) commercial product Stronghold (based
on a different evolution branch, named Sioux up to Stronghold 2.x, and
based on mod_ssl since Stronghold 3.x).

mod_ssl mostly provides a superset of the functionality of all the other
solutions, so it's simple to migrate from one of the older modules to
mod_ssl. The configuration directives and environment variable names
used by the older SSL solutions vary from those used in mod_ssl;
mapping tables are included here to give the equivalents used by mod_ssl.

See also

The mapping between configuration directives used by Apache-SSL
1.x and mod_ssl 2.0.x is given in Table
1. The mapping from Sioux 1.x and Stronghold 2.x is only partial
because of special functionality in these interfaces which mod_ssl
doesn't provide.

When mod_ssl is enabled, additional functions exist for the Custom Log Format of
mod_log_config as documented in the Reference
Chapter. Beside the ``%{varname}x''
eXtension format function which can be used to expand any variables provided
by any module, an additional Cryptography
``%{name}c'' cryptography format function
exists for backward compatibility. The currently implemented function calls
are listed in Table 3.

Notice:This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed again by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Freenode, or sent to our mailing lists.